Industrial heater



c. L. GEHNRICH' INDUSTRIAL HEATER Filed Feb. 1, 1936 iNV ENT OR*Patented Apr. 13, 1937 UNITED STATES PATENT orries 12 Claims.

This invention relates to heaters and more particularly to heaters forsupplying hot gases for industrial uses.

An object of the invention is to provide a light- 5 weight, inexpensive,convenient, eflicient and de-' pendable heater of the above type.

Various other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed.

H) A feature of the invention consists in the elimination of refractorymaterial from the combus-' tion chamber with a consequent reduction inboth the cost and the weight of the unit.

Another feature consists in the arrangement of "l5 the various parts toprevent dissipation and waste of heat.

. Another feature consists in the arrangement of the burner andcombustion chamber so as to prevent the flame from beingextinguished bya sudo den draft.

Another feature consists in the provision of supporting means for thecombustion chamber by which it is spaced from the various ducts so as toeliminate direct transfer of heat.

Other features consist in the various details of construction andcombinations of parts hereinafter more fully set forth.

Although the novel features which are believed to be characteristic ofthis invention will be more 30 particularly pointed out in the claimsappended hereto, the invention itself, as to its objects and advantagesand the manner of its operation, may be better understood by referringto the following description taken'in connection with the ac- 35companying drawing in which one embodiment of the invention has been setforth for purposes of illustration.

In the drawing: v Fig. 1 is a horizontal section'through a heater 40embodying the present invention;

Fig. 2 is a vertical section taken on the line Fig. 3 is a transversesection taken on the line 3-3 of Fig. 1. A 45 In the followingdescription and in the claims,

certain specific terms are used for convenience in ner to be described.The heating chamber in communicates at its intake end with a pipe llthrough which recirculated hot gases or other intake gases such as airmay be supplied. The other end of the heating chamber I is open for thedischarge of the heated gases.

A casing ll surrounds the wall 9 of the heating chamber l0 and is spacedtherefrom to provide an air duct it through which air or other gases tobe heated are passed. The casing i5 is provided with an open end It andat its other end communlcates with a tapered mixing chamber i8 having adischarge port I9. The mixing chamber I8 and the discharge port l9 arepreferably coaxial with the open end I! of the heating chamber ill andreceive gases both from the heating chamber ill and from theair duct 16.The discharge port W of the mixing chamber l8 communicates with theintake of a fan or blower 2| having a housing provided with a dischargeport 22 communicating with a pipe 23 which leads 4 the products ofcombustion to a furnace or other space to be heated. The blower 2i maybe operated from a suitable source of power by means of a belt pulley 24mounted upon a shaft 25 which is journalled in the housing 26 of theblower.

A housing 30 surrounds the casing I5 and is spaced therefrom to providean air duct 3 i. The end 32 of the housing 30 which is adjacent the endiii of the casing i5 is closed so that the air is caused to pass throughthe ducts 3i and IS in the direction indicated by the arrows. The openend 33 of the housing it may be provided with an aperture plate 34having a plurality of apertures 35 through which the air is drawn. Asecond similar aperture plate 38 may be secured in alignment with theaperture plate 3% and may be adjusted as by screws 31 and elongatedslots 38 so as to vary the effective opening of the apertures.

It is to be noted that the open end 33 of the housing so is arranged sothat the air is drawn into the duct 3! over the fan orblower 2i andserves to cool the same as it passes on its way to the heater. Thehousing 30 may be supported in any convenient manner as by brackets 40,and the casing l5 and the wall 9 may be suitably supported by saidhousing.

One or more combustion chambers ii extend diagonally through the housing38, the casing l5 and the walls of the heating chamber it. Thecombustion chambers may be spaced as desired around the heating chamber.In the embodiment shown there are two combustion chambers lovarious 2cated on opposite sides of the heating chamber near 0 e end thereof. Thecombustion chambers 4i are ormed of metal and do not contain anyrefractory material. At their inner ends they are of a size adapted topass the required amount of air for combustion. They are taperedoutwardly and are of greater cross sectional area near the burners so asto reduce the air velocity at the burners for preventing flare back orblowing out of the flame. wall 9 are provided with apertures 42 aroundeach combustion chamber 4|, which apertures are sufficiently large toprovide an air space for the passage of air around said combustionchamber and to prevent the combustion chamber from contacting with themetal walls of the heater.

Each combustion chamber may be supported by a plurality of spaced lugs43 which are secured to the housing 30. The combustion chamber 4| mayeither rest upon or be secured to said lugs. The lugs form the onlymechanical connection between the combustion chamber and the other metalparts of the heater and thereby reduce the heat transfer from thecombustion chamber and provide for independent expansion of thecombustion chamber. A tubular member 44 may be secured to the housing 30and may surround the projecting portion of each combustion chamber 4i,being spaced therefrom to provide a duct 45 through which air forcooling the combustion chamber may pass. Radial bailies 48 may besecured to the combustion chambers 4| to extend partly over the duct 45so as to separate the air streams within and without the combustionchamber and to minimize the'disturban'ce of the flame by air being drawninto the ducts 45. A burner 46 is inserted in the open end of eachcombustion chamber 4i and may be supported by convenient means, such as,brackets 41. The burners 46 are adapted to burn gaseous or liquid 7fuel, preferably under pressure suflicient to cause the flame to projecta substantial distance beyond the tip of the burner. The open end. ofthe combustion chamber provides an air duct around the burner 46 inwhich air for combustion is drawn.

In the operation of this device, suction is created by the blower 2iwhich draws air through the combustion chambers 4| and through the ducts45 and apertures 42 around the exterior of the combustion chambers. Theblower also draws air or hot gases 'through the pipe II and into andthrough the heating chamber [0 to the mixing chamber l8, which gases aremingled with the products of combustion received from the combustionchambers 4i. At the same time air is drawn through the apertures 35 andthe ducts 3i and it into the mixing chamber i8 where it is mixed withthe hot gases from the heating chamber ID.

The air for supporting combustion passes through the combustion chambersand is discharged into the heating chamber. .7 The burners are locatedin the open end of the combustion chambers where the air velocity is thelowest.

Hence, the tendency of the flame to blow out, or

and cold air admitted directly to the heating The housing 30, casing i5and chamber ID. The pipe Ii may be used when desired to recirculate hotair from the oven or other space being heated through the heater.

The cold air which is drawn into the ducts II and 16 serves to cool thecasing and to prevent dissipation of heat therefrom. The cold air drawnover the casing of the blower 2| operates as a cooling medium therefor.The air is preheated to some extent during its passage through ducts 3|and I6 and enters the mixing chamber It at an'elevated temperature. Bycontrolling the relative quantity of air admitted through the ape-rturesl5 and the quantity of hot gases admitted through the pipe ii, theoperation of the device may be varied as desired. Suitable means notshown may also be provided for controlling the rate of combustion in thecombustion chambers cooling means employed prevents the burning out ofthe metal walls of the combustion chamber and at the same time serves topreheat the air prior to introduction thereof into the mixing chamber.The tapered combustion chambers provide a hot metal wall on which theflame impinges. This feature assists in obtaining complete combustion.The entire device is eflicient because of the use of all available heatand the prevention of heat loss through the walls. The metal combustionchamber has a practically indeflnite life and at the same time reducesthe weight and cost of the device.

Obviously, various types of suction means may be employed or in someinstances the blower may be omitted and the device operated by naturalor forced draft or the blower may be connected to provide pressureinstead of suction. A preferred embodiment has been described forpurposes of illustration only.

Although one embodiment of the invention has been described in detail,it is obvious that various changes and modifications may be made thereinas will be apparent to a person skilled in the art. Hence the scope ofthe invention is to be limited only in accordance with the followingclaims when interpreted in view of the prior art.

Iclaim:

l. A heater for supplying hot gases comprising an elongated heatingchamber having intake and discharge openings at opposite ends, an openended combustion chamber having metal walls extending through the sidewalls of said heating chamber and spaced therefrom to provide an airduct around the combustion chamber walls, a burner located in the openend of said combustion chamber to direct a flame therein and means todraw heated gases through said heating chamber, air for combustionthrough the open ended combustion chamber and air for coolingthrough theair duct around said combustion chamber.

2. A heater for supplying hot gases comprising an elongated heatingchamber having intake and discharge openings at opposite ends, an openended combustion chamber having metal walls extending through the sidewalls of said heating chamber, said combustion chamber being inclined tothe axis of said heating chamber in the direction of gas flow andbeingspaced from the walls of said heating chamber to provide an air ductheated gases through said heating chamber, air

for combustion through the open ended combustion chamber and air forcooling through the air duct around said combustion chamber.

3.1 A heater for supplying hot gases comprising an elongatedheatingchamber having intake and discharge openings at opposite ends, an openended combustion chamber having metal.walls extending through the sidewalls of said heating chamber and spaced therefrom to 'provide an airduct around the combustion chamber walls, a

burner located in the open end of said combustion chamber to direct aflame therein and means communicating with said heating chamber to drawheated gasesthrough said heating chamber, air for combustion through theopen ended combustion chamber and air for cooling through the air ductaround said combustion chamber, said combustion chamber being taperedinwardly so that the inner end limits the quantity of air passedtherethrough and the velocity of the air is reduced opposite the burnerto prevent disturbance of the flame.

4. A heater for supplying hot gases comprising an elongated heatingchamber having intake and discharge'openings at opposite ends, a taperedopen ended combustion chamber having metal walls extending through theside walls of said heating chamber and spaced therefrom to provide anair duct around the combustion chamber walls, a burner located in theopen end of said combustion chamber to direct a flame therein, a

suction blower communicating with the discharge end of said heatingchamber to draw heated gases through said heating chamber and to drawair for combustion through the open ended combustion chamber and air forcooling through the airwduct around said combustion chamber and membersforming a pair of concentric air ducts around said'heating chamber, oneof said ducts havin an open end adjacent said blower arranged so thatthe cool air is drawn over the blower on its way to said duct, saidducts intercommunicating so that said air is drawn over said blowerthrough the outer duct and thence in the reverse direction through theinner duct.

5. A heater for supplying hot gases comprising an elongated heatingchamber having air intake and discharge openings at opposite ends, asuction blower communicating with the discharge opening, a combustionchamber communicating with said heating chamber and adapted to supplyhot combustion gases thereto and members forming a pair of communicatingconcentric air ducts around said heating chamber through which airpasses successively in opposite directions, the inner duct terminatingin a position to discharge air to said blower and the outer duct havingits intake opening in a position to draw cold air over theblower-housing on its way to said duct.

6. A heater for supplying hot gases comprising an elongated heatingchamber having air intake and discharge openings at opposite ends, 'acombustion chamber communicating with said heating chamber to supply hotcombustion gases thereto, a mixing chamber communicating with saiddischarge opening to receive the hot gases from said heating chamber, asuction blower communicating with said mixing chamber to draw the hotgases-therefrom, and members disposed around said heating chamber andforming a pair of concentric air ducts through which air flowssuccessively in opposite directions, the outer through which air isdrawn successively in opposite directions for extracting heat from thewalls of said heating chamber, the inner duct having a discharge portadjacent the discharge port of said heating chamber, an open endedcombustion chamber extending through said members and through the sidewall of said heating chamber and spaced therefrom to provide an airpassage 1 around the outer surface 01 said combustion chamber, a burnerlocated in'the open end of said combustion chamber and blower meanscommunicating with said heating chamber, inner duct and combustionchamber to pass hot gases through said heating chamber, air for coolingthe walls of said heating chamber through said ducts,

air for combustion through said combustion chamber and air for coolingthe walls of said combustion chamber throiigh the air passage aroundsaid walls.

'8. A heater for supplying hot gases comprising an elongated heatingchamber having inlet and discharge ports, members around said heatingchamber forming a pair of concentric air ducts through which air isdrawn successively in opposite directions for extracting heat from, the-"walls of said heating chamber, a mixing chamber receiving gases fromsaid heating chamber and from said ducts, an open ended, combustionchamber extending through said members and through the side wall of saidheating chamber and separated therefrom to provide an air pas-- sagearound the outer surface of said combustion chamber, a burner located inthe open end of said combustion chamber and means communicating withsaid mixing chamber, inner duct and combustion chamber to pass hot gasesthrough said heating chamber, .air for cooling the walls of said heatingchamberthrough said ducts, air for combustion through said combustionchamber and air for cooling the walls of said combustion chamber throughthe air passage around said walls, said combustion chamber being taperedso that the quantity of air is limited by the cross-sectional area ofits inner end and the air velocity is reduced at the outerendoppositethe burner.

9. A heater for supplying hot gases comprising an elongated heatingchamber, an open ended combustion chamber extending through the sidewalls of said heating chamber and spaced therefrom to provide an airduct around the outer surface of said combustion chamber, a mixingchamber communicating withsaid heating chamber and adapted to receivehot gases therefrom, members disposed around said combustion chamber andforming a pair of concentric air ducts through which air flowssuccessively in opposite directions, on its way to said mixing chamber,and a suction blower communicating with said mixing chamber -to drawcombustion gases through said combustion chamber, gases for heatingthrough said heating chamber and air through all of said ducts into saidmixing chamber, the

outer concentric duct having an intake opening located to draw air oversaid blower on its way I walls to provide an air duct around the outersurface of said combustion chamber and to prevent direct transfer ofheat to said walls, a mixing chamber communicating with said heatingchamber and adapted to receive hot gases therefrom, members disposedaround said combustion chamber and forming a pair of concentric airducts through which air flows successively in opposite directions, onits way to said mixing-chamber, and a suction blower communicating withsaid mixing chamber to draw combustion gases through said combustionchamber, gases ior heating through said heating chamber and air throughall of said ducts into said mixing chamber, the outer concentric ducthaving an intake opening located to draw air over said blower on its wayto said duct. 11. A heater for supplying hot gases comprising anelongated heating chamber, means to supply gases thereto for heating asuction blower adapted to draw the hot gases therefrom, members disposedaround said heating chamber and forming a pair of concentric air ductsthrough which air flows successively in opposite directions, forextracting heat from the walls of said heating chamber, an open endedcombustion chamber direct a flame therein.

12. A heater for supplying hot gases comprising an elongated heatingchamber having inlet port to receive gases for heating and a dischargeport for the hot gases, members around said heating chamber forming apair of concentric air ducts through which air is drawn successively inopposite directions for extracting heat from the walls of said heatingchamber, the outer duct having an adjustable inlet port comprising apair of relatively movable aperture plates, an open ended combustionchamber extending through said members and through the wall of saidheating chamber to supply hot gases thereto,

a burner located in the open end of said combus tion chamber and asuction blower associated with said heating chamber adapted to draw hotgases through said heating chamber, air for cooling the walls of saidheated chamber through said ducts and air for combustion through saidcombustion chamber.

CHARLES L. GEHNRICH.

